Question

A beam of unpolarized light passes through a tourmaline crystal A and then it passes through a second tourmaline crystal B oriented so that its principal plane is parallel to that of A. The intensity of emergent light is $I_0$. Now B is rotated by $45^\circ$ about the ray. The emergent light will have intensity $(\cos 45^\circ = \frac{1}{\sqrt{2)$

• A. $\frac{I_0}{2}$
• B. $\frac{I_0}{\sqrt{2$
• C. $\frac{\sqrt{2{I_0}$
• D. $\frac{2}{I_0}$

Hint:

Logic Tip: Malus's Law ($I = I_{max} \cos^2 \theta$) creates a very predictable pattern: At $0^\circ \rightarrow I_{max}$ At $45^\circ \rightarrow I_{max}/2$ At $60^\circ \rightarrow I_{max}/4$ At $90^\circ \rightarrow 0$ (crossed polarizers).

Answer 1

The Correct Option is A